This invention relates to a device for holding optical lenses and aims to offer a holder which allows easy exchange of lenses even in the narrow space between the holding device and an optical apparatus per se and which can position lenses with a higher precision for proper alignment in the optical instrument.
An example of an optical apparatus is described referring to a microfilm reader-printer shown in FIG. 1. The light from a lamp chamber 3 illuminates a microfilm 2 interposed between film carriers 1 or a pair of glass plates. The image of the microfilm 2 is enlarged by a lens 4, reflected by mirrors 5, 6 and 7 and focused on a screen 8. Plural conveyor belts 9 carry an electrophotosensitive paper (not shown) in the direction from the backside of the drawing to the front. Along the direction of the conveyor belt 9, a charging device, an exposure area, a development device and a fixing device are arranged consecutively in that order (not shown) to construct an electrophotographic copier. When the mirror 6 is pivotally moved to the position indicated by the two-dot chain line in the figure, the image of the microfilm 2 is enlarged by the lens 4, reflected by the mirror 5 and a mirror 10 and caused to focus on said exposure area. Then, the electrophotographic copier prints a copy of the image. In such a microfilm reader-printer, images can be observed on the screen 8 and also reproduced in hard-copy by the electrophotographic copier. In the figure, the reference numeral 11 denotes a main body cage, and 12 the space for mounting a holder.
Conventional microfilm reader-printers or other optical apparatuses have such defects as follows:
(1) In inexpensive devices, the lens 4 was either fixed directly on the main body cage 11 or attached thereto with a simple device such as a screw-type device. If it is fixed, the lens can not be exchanged nor is it possible to change magnification. Even if it is detachable, a simple attachment is used to save cost, and the workability of the attach/detach operation is not quite satisfactory. Furthermore, as the space 12 is extremely limited, difficulty in replacement or exchange work increases. PA0 (2) In expensive devices, on the other hand, there is generally provided a sophisticated lens exchanging device which can be attached with a plurality of lenses. If plural lenses of different magnifications are once mounted on such an exchanging device, a lens of any magnification may arbitrarily be selected and used. However, the work of attaching or detaching lenses on such a lens exchanging device must still be performed within the extremely limited space 12, thus posing a problem. Furthermore, the maximum number of the lenses mountable on such a lens exchanging device is predetermined quite rigidly. If an optical apparatus already has a lens exchanging device which can mount up to two lenses and a user still wants to increase the number of lenses, the user may remove this device and exchange it for another device which can mount a larger number of, for instance three, lenses. But this is neither practical nor economical to the user.